A.that B.what C.it was D./

题目

A.that B.what C.it was D./
_A.__ the dog was the first animal to be domesticated is generally agreed upon by authorities in the field.

答案

答案是a.1.因为所填的介词因在这引导一个主语从句the dog was the first animal to be domesticated.在英语关系从句中,只有that可以引导主语从句,放在句首.2.因为主语从句是一个完整的句子,而what在定语从句中是充当...